遮荫对黑茶藨子叶片形态结构和光合特性的影响

以黑茶藨子为试验材料，通过人工遮荫的方式，研究了不同遮荫强度（全光照、20%和60%遮荫）和遮荫时间（初期、中期和后期）对黑茶藨子叶片形态解剖结构和光合特性的影响。结果表明：（1）20%、60%遮荫处理的叶片厚度均显著低于全光照处理，上下表皮厚度则高于全光照处理；随着遮荫强度的加大，栅栏组织与海绵组织厚度比值大小均呈减少趋势，随着遮荫时间的延长，呈增加趋势。（2）遮荫初期和中期，20%遮荫处理的叶片净光合速率（P_n）比全光照和60%遮荫处理的值略高，但差异并不显著（P>0.05），其蒸腾速率（T_r）、水分利用效率（WUE）也略有增加；但是，60%遮荫处理的叶片净光合速率（P_n）显著低于全光照处理（P<0.05）。遮荫后期，60%遮荫处理的叶片净光合速率（P_n）显著高于全光照处理，且水分利用效率（WUE）、气孔导度（G_s）、蒸腾速率（T_r）均显著高于全光照和20%遮荫处理。综上所述，遮荫处理导致叶片厚度减少，海绵组织比例增加，有利于减少透射光中的光量子丧失，提高光能利用效率；生长早期和中期作20%轻度遮荫处理，后期作60%中度遮荫处理能提高植株对光和水分的利用效率、维持较高的光合速率、延缓衰老。

Effects of Shading on Anatomical Structure and Photosynthetic Characteristics of Ribes nigrum L. Leaves

We studied the anatomical structure and photosynthetic characteristics of Ribes nigrum L. leaves under different shading degrees(full sunlight, 20%, 60% of shading degree) and different shading time(early, middle, and late). The thickness of leaf under 20% and 60% shading treatments were lower than that under full sunlight treatment with significant differences, and the epidermis thickness were higher in the opposite way. The ratio of palisade tissue to spongy tissue decreased as the increase of shading degree, which increased with the extension of shading time. In early and middle shading stage, the photosynthetic rate(P_n) of 20% shading treatment was little higher than that under full sunlight treatment, but there was no significant difference(P>0.05), the transpiration rate(T_r) and water use efficiency(WUE) were changed in the same circumstances. The P_n of 60% shading treatments were lower than that under full sunlight treatment significantly(P<0.05). In late shading stage, the P_n of 60% shading treatments were significantly higher than that under full sunlight treatment(P<0.05), and the WUE, T_r and Stomatal Conductance(G_s) were higher than that under full sunlight and 20% shading treatment. Therefore, these changes of the anatomical structure were helpful for R.nigrum to improve the utilization of luminous energy, and different shading time resulted in the change of photosynthetic characteristics. With the photosynthetic characteristics and anatomical structure of R.nigrum leaves, the R.nigrum should be shadowed in different degrees(20% shading treatment in early and middle stage, 60% shading treatment in late stage) during the different stages, which can improve the efficiency of using light and water, maintain higher photosynthetic rate and retard the aging process.